Because water is a very very very very very unusual substance ... It's the only known substance whose solid form is less dense than its liquid form near the same temperature.
In other words, water is the only known substance for which a solid lump of it floats in a liquid glass of it.
If that were not true ... if the behavior of the density of water around its freezing temperature were the same as the density of all other known substances ... then life on Earth would be impossible.
Think about that for a while ! Ya gotta admire whoever it was that designed water !
A because the toaster converts electrical energy into heat energy and, after the bread has been heated for sufficient time, toasts pop out, ready to be buttered. And converting means transforming.
